I'll have a 6' long by 7' Riser, 16" off the ground. It will have one step, 8" high up, 12" deep, by 24" wide on the side edge next to the front to get up. The rest of the sides will be a straight 16" up from the floor to the top of the riser. My question is, do most of you just carpet the sides of the riser, even at 16" high mostly around, or just carpet the top/steps, and then drywall the sides and put trim around it? The front side will have an outlet and network tap in it, and possible a light on the other side.

I can't recall seeing a riser that had drywalled sides, but I don't see any reason why you couldn't do it. I guess the biggest drawback would be that the relatively soft drywall might be prone to being scratched and scarred by shoes.

If the sides of the riser are exposed, a lot of folks here finish them with wood trim. Gonzo's thread is an excellent (if elaborate) example of this: http://www.avsforum.com/avs-vb/showthread.php?t=719146&page=12. Post 356 has a nice photo of the finished riser.

A lot of risers also have carpeted sides, which I think is especially appropriate for shorter risers where the intent is that it really just blend in with the floor. For a 16" tall riser, I would personally trim it out with wood and let it contribute to the overall effect of the room.